Communications systems need a transmission medium for signals, and the transmission medium is very often made up of multiple conductors. The presence of these multiple conductors can be exploited in order to enhance various features of the communications system, such as the transmission capacity or immunity to noise, among others. One of the ways of exploiting a multi-conductor medium is to use orthogonal modes, for which it is necessary to inject signals in that medium in the right way.
The device of the present disclosure is designed for being able to apply the method specified in Spanish Application No. 200702256 relating to a “Method for increasing the performance of a communications system on a medium made up of multiple conductors.” As with this application, the description of the present disclosure uses various conventional concepts which are commented on below. “Mode” is understood to be the injection of voltage or current on a selective combination of conductors, reference plane, or both. Likewise, “orthogonal multi-injection” is defined as being an injection of multiple modes orthogonal to each other. The injection modes are divided into a common mode, differential modes, and pseudo-differential modes. The common mode is that which causes circulation of currents via the reference plane. The differential modes consist of injection by a conductor and collection of the return via the other, while the pseudo-differential modes consist of injection of voltage or current between one or more conductors and return via one or more conductors different from those used for the injection, the number of conductors used in this case being greater than two.
There exists in the state of the art some references with methods intended to increase the performance of a communications system when the medium is a multi-conductor which leave unsolved the problem of carrying out the injection in that medium. The present disclosure solves this shortcoming and focuses on the specific way of carrying out voltage injection on that medium in order to achieve orthogonality among the injections; it therefore solves the stated problem and as a consequence it is not anticipated by the documents existing in the state of the art.
Moreover, the state of the art also contains references on capacitive couplers, which do not anticipate the teachings of the present disclosure. One of these references is European Application No. E05773887, “Capacitive coupling device for data transmission equipment to a phase of an electrical power line.” This reference describes a method of capacitive coupling conceived for medium voltage lines where the safety measures are very strict. The coupling needs a ground connection and it also couples the signal in “single-ended” mode, in other words, it injects the signal in a single phase with respect to ground. This does not take away any novelty or inventive level from the present disclosure, since the latter is capable of injecting in differential or pseudo-differential modes or in common mode, carrying out multi-injections of signals on several conductors, including or not the reference plane normally connected to ground.
Another document of the state of the art is the Spanish Publication No. 2204334A1, “Medium voltage equipment with capacitive coupling system.” As with the previous reference, the publication describes a method of medium voltage capacitive coupling in order to couple the signal to a phase of the medium voltage network. This does not affect the novelty or inventive level of the present disclosure, since the publication cannot be used for multiple injections in a multi-conductor medium with reference plane, where the injections are differential, pseudo-differential, or common mode.
U.S. Pat. No. 4,383,243, “Powerline carrier control installation,” describes how to couple a signal from a single control tone on the electric line by means of capacitive coupling. The circuit of this patent improves adaptation to the impedance of the medium but cannot be used for multi-injection and so does not take away any novelty or inventive level from the present disclosure.
U.S. Pat. No. 6,693,803, “Coupling device for low-rate carrier current transmission system,” reveals a method of coupling for carrying out transmissions/receptions of modulations of a single carrier. The coupling is carried out using a transformer and a coupling capacitor, being a differential injection made between phase and neutral. This circuit cannot be used for carrying out orthogonal multi-injections in multiple conductors, and it therefore does not anticipate the present disclosure.
Finally, another example of a capacitive coupler of the state of the art is U.S. Publication No. 2004/0056734, “Medium voltage signal coupling structure for last leg power grid high-speed data network,” which describes a coupler for medium voltage aerial lines, placing the emphasis on the safety mechanisms necessary for the handling of this type of line. As with the previous references, this coupler does not anticipate the multi-injection device of the present disclosure.